Busted sheave, odd size, what to do?

[hd002e]

At the end of my z-spar boom is a casette of four sheaves that are used for outhaul, reefing and the topping lift. The sheaves are as old as the boat and the black plastic has cracked. The other day my reefing line got stuck in the opening and gave me a bit of a hassle as I couldn’t reef.

The size of these sheaves are kind of odd:

OD: 44mm
ID: 8mm
Width: 11mm

I looked up mauri pro and a few other rigging suppliers but no one seems to have the exact size. I am thinking of having them machined out of Delrin using a lathe.

My questions are:
- what is a good place to find sheaves?
- is Delrin a good UV stable material?
- should I get them machined out of stainless steel instead?

Thanks!

[Unity]

Delrin is a great material for sheaves. We many many that are custom machined for us. Not all machine shops will work them though. Call your local machine shops. Also consider purchasing your Delrin online - maybe a large enough piece to make several. Often cheaper than having the shop source the materials. And often these shops are CNC so much of the cost is setup - making 1 or 10 can be very similar in machining cost.

[jannw]

delrin is a piece of piss to machine and is a good choice. Any manual machine shop can do it without much difficulty ... hell, I can do it on my hobbyist lathe.

[hellosailor]

Metric sizes? Beneteau? Could be French parts that you won't find in the US. Beneteau customer service is very good at things like supplying spares (not totally unreasonable) or sources. You might very well be able to order them from the original supplier, or Beneteau, or have a machine shop make a complete replacement set.

Or if you have some computer skills, you can draw them up and emachineshop.com will fab them from your files. (They supply free CAD software.) If you go to a local machine shop and they mention aluminum "because we've got it in stock" beware. The aluminum they have in stock probably will degrade in salt air very quickly, unless it is hard anodized, or after that wears. Extra points for Delrin and the like.(G)

Depending on where you live, maybe $20-75 each, I'm guessing.

[Cheechako]

They dont have to be exact at all. Whatever fits, larger is smoother turning. Aluminum may be available.
Have you checked other spar makers sites?

[steamgoat]

Zephyrwerks, I think that’s correct,they can make any size to order.

[Cheechako]

Another thought, find a used block at a used boat equipment place, remove the sheave?
Ebay: 39mm aluminum sheave: https://www.ebay.com/itm/NAUTOS-9235...ox!98290!US!-1

44mm, $1.95: https://www.ebay.com/itm/Sheave-1-3-...0AAOSwqo5beFVQ

40mm Nylon, $8.99: https://www.ebay.com/itm/40mm-Boat-P...EAAOSwRgJXlC1w

[Don C L]

I had this same problem when I busted a phenolic sheave at the masthead of my 50 year old boat. I called Ballenger Spars in Watsonville, CA and the owner answered the phone. He knew exactly what I was talking about, and the size and knew it was not on the shelf. They made me a new set. I don’t recall the price but it was reasonable. Any rigging issue now I highly recommend those guys.

[JPA Cate]

hd002e,

If one of those has gone due to UV, the others in the box are probably close to the same condition. Maybe Beneteau can sell you a whole new box, with new sheaves. I would seriously consider replacing all of them, however you go about it. It's a pita to un-reave and re-reave the lines, might as well do it only the one time.

I apologize for spending your money for you! It was just a thought.

Ann

[RaymondR]

I have the same problem with masthead sheaves for an Isomat mast head. Only place I could find spares was Rig Rite in the US so I paid A$28 for 100 mm of 90 MM of round bar Delrin and went to a machine shop. They want A$80 for machining so I figured that with item cost, shipping, clearance etc it was probably going to cost me that from Rig Rite and I get it in one day. I bought 100 mm so that I will have some to machine up some spares later.

[svHyLyte]

Originally Posted by hd002e

At the end of my z-spar boom is a casette of four sheaves that are used for outhaul, reefing and the topping lift. The sheaves are as old as the boat and the black plastic has cracked. The other day my reefing line got stuck in the opening and gave me a bit of a hassle as I couldn’t reef.

The size of these sheaves are kind of odd:

OD: 44mm
ID: 8mm
Width: 11mm

I looked up mauri pro and a few other rigging suppliers but no one seems to have the exact size. I am thinking of having them machined out of Delrin using a lathe.

My questions are:
- what is a good place to find sheaves?
- is Delrin a good UV stable material?
- should I get them machined out of stainless steel instead?

Thanks!

Garhaurer will either have or can make up very inexpensively, the sheaves you need. Per JPA Cate's suggestion, replace all four. Odd's are the sheaves at the goose-neck end of the boom are questionable as well so you might want to replace them too. We have been very happy with Garhaurer's products which are quite inexpensive but of good quality.

FWIW...

[Privilege]

I'm with Cheechako, they don't have to be exactly the same size. The most important size is the diameter. They have to be wide enough to fit snugly in the space. If they are not, the sheave can be pushed over to one side and when the line is loaded and pulled at any sort of angle, the line can then compress down the gap left at the side of the sheave and get stuck - the same as you had happen with your broken one.
Also, although this may sound obvious, convert your 11mm to 7/16" and search for that. You'll get different results.

[Unity]

Originally Posted by Privilege

Also, although this may sound obvious, convert your 11mm to 7/16" and search for that. You'll get different results.

Great suggestion. I had same issue trying to source 12mm chain in the US, and switching to 7/16" I found exactly what I wanted, and it was with 0.005" and works great.

[techmans]

Found this using imperial measure,

https://www.fisheriessupply.com/scha...sheaves-delrin

the 5/16 x 1 7/16 x 17/32 is slightly wider ( got sandpaper? ) and slightly smaller in dia. and cost you all of $ 14.26. Buy a few spares to bugger one up.

[Sailorbob8599]

Originally Posted by RaymondR

I have the same problem with masthead sheaves for an Isomat mast head. Only place I could find spares was Rig Rite in the US so I paid A$28 for 100 mm of 90 MM of round bar Delrin and went to a machine shop. They want A$80 for machining so I figured that with item cost, shipping, clearance etc it was probably going to cost me that from Rig Rite and I get it in one day. I bought 100 mm so that I will have some to machine up some spares later.

My masthead sheaves failed for the same reason so I made a s.s. cover for the top of the spar to provide shelter for the sheaves from UV. damage. The s.s. is 16ga so I can mount other items on it if I wish, such as an anchor light & Windex vane. Maybe even an antenna . . .